Date: Sun, 02 Jul 2000 14:53:46 -0700 From: Kent Stewart <kstewart@3-cities.com> To: David Gilbert <dgilbert@velocet.ca> Cc: freebsd-stable@freebsd.org Subject: Re: Dump takes ages on SCSI. (several times faster on IDE) Message-ID: <395FB9EA.E3115939@3-cities.com> References: <14687.42282.873585.2561@trooper.velocet.net>
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David Gilbert wrote: > > I have a PIII/450 with a venerable Adaptec 2940UW and a Quantum 9G > SCSI disk. > > Recenly, I was generating many crash dumps and was using a serial > console (so I was watching them). I came to a point in my debugging > where I needed another PCI slot, so I removed the 2940 and loaded an > IDE drive with the same build of FreeBSD. > > I then noticed that the IDE would crashdump somewhere around 10 times > faster than the SCSI disk. > > Why? Can the SCSI speed be improved? It depends on what 2940 and what IDE drive you are talking about. I have a Maxtor UDMA66 that is 20MB/s faster in some situations than my 2940uw with an older IBM drive probably comparable to your Quantum. The IBM benchmark peaks at 8MB/s and has a smaller cache. The random performance of the IBM is many times the Maxtor (10x at least); however, on sequential read/writes the Maxtor really shines. I think that a dump would be comparable to my sequential write situation. It was explained to me that the scsi can schedule random read/writes and the IDE can't. A server needs random read/writes and uses the scsi to its benefit. One of these new lvd controllers and drives (80+MB/s min) would do wonders to your performance during the dump. Kent > > Dave. > > -- > ============================================================================ > |David Gilbert, Velocet Communications. | Two things can only be | > |Mail: dgilbert@velocet.net | equal if and only if they | > |http://www.velocet.net/~dgilbert | are precisely opposite. | > =========================================================GLO================ > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-stable" in the body of the message -- Kent Stewart Richland, WA mailto:kstewart@3-cities.com http://www.3-cities.com/~kstewart/index.html FreeBSD News http://daily.daemonnews.org/ SETI(Search for Extraterrestrial Intelligence) @ HOME http://setiathome.ssl.berkeley.edu/ Hunting Archibald Stewart, b 1802 in Ballymena, Antrim Co., NIR http://www.3-cities.com/~kstewart/genealogy/archibald_stewart.html To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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